Type-2 diabetic subjects in the early stages of non-proliferative retinopathy (level 30 to 35 ETDRS) included in the clinical trial "Validation of a predictive model to estimate the risk of conversion to clinically significant macular edema and/or vision loss in mild nonproliferative diabetic retinopathy in diabetes type 2" (Protocol number: PTDC/SAU-OSM/72635/2006; ongoing at AIBILI Clinical Trial Center).